The Mr. Heater 20K Blue Flame Dual Fuel is the better gas wall heater overall, rated 4.2 to 2.6. The Mr. Heater 20K Blue Flame Dual Fuel leads on warranty, controls and fuel. The Mr. Heater 20K Blue Flame Dual Fuel costs $10.70 less ($199.99 vs $210.69).
A thermostat blue flame heater for a living room or cabin of up to about 700 sq ft that may switch between propane and natural gas. The long warranty sets it apart.
Amazon $199.99A plain manual blue flame heater for a natural gas living room or den. Most buyers will get more for the money from a thermostat model.
Amazon $210.69Prices were last checked November 2, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Each factor is scored 0-100 against the same fixed reference points for every vent-free gas wall heater; a clear win is highlighted. How we rank explains each one.
| Factor weight | Mr. Heater 20K Blue Flame Dual Fuel | Dyna-Glo BF20NMDG-4 20K Blue Flame |
|---|---|---|
| Overall rating | 4.2/5 | 2.6/5 |
| Value 30% | 64 $10 per 1,000 BTU ($199.99, 20,000 BTU) | 61 $10.53 per 1,000 BTU ($210.69, 20,000 BTU) |
| Heat output 15% | 50 20,000 BTU/hr | 50 20,000 BTU/hr |
| Controls 20% | 75 thermostat, electronic ignition | 25 electronic ignition |
| Fuel 5% | 100 runs on propane or natural gas | 0 natural gas only |
| Warranty 30% | 100 5-year warranty | 0 1-year warranty |
| Mr. Heater 20K Blue Flame Dual Fuel | Dyna-Glo BF20NMDG-4 20K Blue Flame | |
|---|---|---|
| Heat | ||
| Venting | Vent-free | Vent-free |
| Heat type | Blue flame | Blue flame |
| Maximum input | 20,000 BTU/hr | 20,000 BTU/hr |
| Minimum input | - | 10,000 BTU/hr |
| Heating area claim | 700 sq ft | 700 sq ft |
| Fuel and controls | ||
| Fuel | Dual fuel | Natural gas |
| Thermostat | Yes | No |
| Blower | No | No |
| Ignition | Electronic (battery) | Electronic (battery) |
| Needs an outlet | No | No |
| Oxygen depletion sensor | Yes | Yes |
| Build | ||
| Warranty | 5 years | 1 year |
| Released | 2018-10 | - |
